Enhanced Electrocaloric Response in Electrostatically Frustrated Ferroelectrics

The electrocaloric effect (i.e., the temperature change of a material upon the adiabatic application of an electric field) can be large in ferroelectric compounds, to the extent of offering an eco-friendly alternative to current, polluting and noisy, refrigeration technologies. So far, ferroelectric-based electrocaloric devices employ materials (from perovskite oxides to polymers) that have been known for decades. At the same time, recent studies have shown that the functional response of a ferroelectric can be drastically enhanced by controlling its mechanical and electric boundary conditions. Here, we use atomistic second-principles simulations to quantify how much the electrocaloric effect benefits from such an enhancement. Using PbTiO3/SrTiO3 ferroelectric/dielectric superlattices as representative model systems, we predict that temperature changes can indeed be increased significantly (more than two times at room temperature), suggesting electrostatic engineering-to induce very reactive frustrated ferroelectric states-as a promising route for electrocaloric optimization.